【作者】 尹增德；

【导师】 蒋金泉；

【作者基本信息】 山东科技大学 ， 采矿工程， 2007， 博士

【摘要】 本文运用现场实测、物理模拟、数值模拟与数学、力学理论研究等方法，对缓及倾斜煤层一次采全厚条件下，覆岩破坏特征受覆岩岩性、岩性结构、工作面几何参数、断层及时间等因素影响的规律进行了研究。在三维弹塑性有限元软件基础上增加粘弹塑性分析功能，定义了点安全度岩层破坏判据，对四类典型岩性结构覆岩在采动边界上的破坏规律进行了研究，最后进行了相关应用研究。研究获得了以下主要结论：(1)导水裂缝带高度受开采方法、采厚、覆岩岩性、岩性结构、工作面几何参数、时间及断层影响的规律。开采方法不同一次采出厚度不同，采厚与破坏高度呈非线性关系；随岩性强度由高到低，破坏高度逐渐减小；随岩性结构由坚硬-坚硬型、坚硬-软弱型、软弱-坚硬型到软弱-软弱型，破坏高度逐渐降低；在非充分采动条件下工作面短边长度决定了破坏高度，在充分条件下则影响很小；随时间增长覆岩破坏高度有一个上升、最大高度、回降、稳定的过程；断层处于破坏带内或外其影响程度不同。(2)导水裂缝带形态受覆岩岩性、岩性结构、工作面参数及边界支承条件影响的规律。随岩性强度由高到低，“马鞍形”由明显变为不明显；岩性结构决定了覆岩破坏边界自下而上向采空区还是向煤壁前方扩展；工作面短边长度决定是“拱形”还是“马鞍形”，边界支承条件不同决定了形态不同。建立了高差计算模型与典型形态系列模型。(3)覆岩破坏各带及亚分带的破坏与高度特征，各亚分带与注水漏失量的关系。(4)覆岩破坏侧边界与煤体状态关系。覆岩破坏侧边界主要由煤体破坏边界决定，提出了覆岩破坏边界移动距描述参数及确定方法。(5)提出了反映岩层厚度与强度的综合抗压强度指标与覆岩分类方法。(6)建立了反映覆岩岩性、岩性结构、工作面几何参数对导水裂缝带高度影响的描述方法，并相应推导了综放开采导水裂缝带高度的预测公式。(7)提出了中硬覆岩中厚煤层上行开采基本层间距及可行性区间划分准则与评价方法、边界断层防水煤柱留设方法、瓦斯抽放方案确定原则等。研究成果对覆岩破坏理论研究、安全高效生产具有重要的理论价值与实用价值。更多还原

【Abstract】 In this dissertation, various methods, such as in situ measurement, physical and numerical simulation, are applied for the analysis of the failure characteristics of the overburden strata by coal mining under the conditions of slight dipping or dipping seams and mining the whole seam one time. In this analysis, various affecting factors, such as the properties of the overburden strata, the structures of strata, the parameters of working faces, faults and time, are considered in detail. In order to study the failure characteristics of overburden strata, the three-dimensional finite element program is written in Fortran. The program can be used for the analysis of the viscous-elastic and viscous-plastic deformation and failure. This program can also be used for considering faults and weak structures of rocks and obtaining the point safety factors, which are used to determine the failure state. The four models of considering overburden strata structures, such as hard-hard strata, hard-weak strata, weak-hard strata and weak-weak strata, are analyzed in detail. The different failure characteristics of overburden strata are obtained. The following conclusions are drawn.The relationship of the water conducting height of overburden strata and various affecting factors, such as the mining method, the structures of rock strata, the parameters of the working face and faults, are established. The failure height of overburden strata changes nonlinearly with the mining thickness of coal seam. The failure heights are related to the strength of overburden strata. The higher the strength of the overburden strata is, the less the failure height of the overburden strata is. And the failure height of overburden strata is also related to the structures of overburden strata. For non-fully mining, the failure height is determined by the short side of the working face. For fully mining, this effect is less. In addition, with the time elapsing, the failure height reaches the maximum value, then decreases and becomes a stable value. For the faulted zone, the variations of the failure height are different.The failure state of overburden strata is related to rock properties, the structures of strata, the parameters of working faces and the supporting conditions. If the strength of rocks is high, it is possible that the saddle-shaped failure boundary does not exist. The failure boundary of overburden strata is determined by the strata structures. The arch or saddle-shaped failure boundary is determined by the length of short sides of the working face. The failure boundary also changes with different supporting conditions. The models of calculating failure heights and the classical shapes are developed.The sub-zones of overburden strata failure and the strong, medium and weak sub-zones are researched by the water injected volume in the borehole.The relationship of the lateral boundary of overburden strata and the state of coal bed is established. The lateral boundary of overburden strata is determined by the failure state of the coal bed. The parameters and method of determining the failure boundary of overburden strata are presented.The strength index of comprehensive compressive strength and the classification method of overburden strata are presented by considering strata thickness and strength.The method of determining the influence of different factors on the failure height is also presented. These factors include the strata properties and structures, the parameters of the working face. The formulae of predicting the failure height for fully machined mining are proposed.For ascending mining of thick coal seam having medium-hard overburden strata, the standards of determining the distances of different fundamental layers are presented. Meanwhile, the methods are also proposed for determining the width of the coal pillar preventing water inrush and extracting methane from coal seam.The above-mentioned results of failure characteristics of overburden strata are much useful for safe mining of coal.更多还原